CN103645509B - The inverting of compact reservoir pore components and S-Wave Velocity Predicted Method - Google Patents

Abstract

The invention provides the inverting of a kind of compact reservoir pore components and S-Wave Velocity Predicted Method, the method calculates each pore components a by petrophysical model _ncorresponding P-wave And S analog rate Vp _nwith Vs _n, and calculate Vp _nwith the difference of the velocity of longitudinal wave Vp obtained that logs well, ask for also saved differences and reach minimizing pore components a _nwith shear wave analog rate Vs _n.The empirical fit mode that the method is more traditional has more theory advantage.

Description

The inverting of compact reservoir pore components and S-Wave Velocity Predicted Method

Technical field

The invention belongs to seismic exploration technique field, particularly, relate to the inverting of a kind of compact reservoir pore texture and S-Wave Velocity Predicted Method.

Background technology

In compact reservoir, the structure (pore components) of hole has more decisive influence than size (factor of porosity) elastic modulus to rock of hole; Meanwhile, pore texture more can determine the perviousness of compact reservoir than pore size, and then affects the economy of fine and close hydrocarbon-bearing pool exploitation.The parameter of quantificational expression pore texture is pore components, and it is defined as the minor axis of hole and the ratio of major axis, represents the shape of hole; Close to 1, aspect ratio represents that pore shape is tending towards spherical, much smaller than 1, aspect ratio represents that hole is tending towards long and narrow; In rock, long and narrow void ratio spherical void more can increase the penetrating power of medium.

The core of pore texture inverting is to set up petrophysical model, when known mineral constituent percent by volume, mineral and pore fluid elastic property and aspect ratio, the bulk modulus of quantitative calculating rock and modulus of shearing, and then the P-and S-wave velocity calculating rock.At present, in earthquake rock physics field, consider that the petrophysical model of mineral grain and pore components and application thereof mainly comprise:

(1), eFFECTIVE MEDIUM THEORY

Kuster and give equivalent elastic modulus computing formula:

$(K_{\mathrm{KT}}^{*}-K_m)\frac{(K_m+\frac{4}{3}{\mathrm{\μ}}_m)}{(K_{\mathrm{KT}}^{*}+\frac{4}{3}{\mathrm{\μ}}_m)}={\mathrm{\Σ}}_{i=1}^N{x}_i(K_i-K_m)P^{\mathrm{mi}}=0---\left(1\right)$

$({\mathrm{\μ}}_{\mathrm{KT}}^{*}-{\mathrm{\μ}}_m)\frac{({\mathrm{\μ}}_m+{\mathrm{\ζ}}_m)}{({\mathrm{\μ}}_{\mathrm{KT}}^{*}+{\mathrm{\ζ}}_m)}={\mathrm{\Σ}}_{i=1}^N{x}_i({\mathrm{\μ}}_i-{\mathrm{\μ}}_m)Q^{\mathrm{mi}}=0---\left(2\right)$

Wherein, formula (1) and (2) the right, N kind mineral are with percent by volume x _isummation; P ^miand Q ^mirepresent the form of i-th kind of mineral in background media m respectively, its expression formula comprises the aspect ratio of mineral grain and hole.

(2), difference EFFECTIVE MEDIUM (Differential Effective Medium) is theoretical

The difference EFFECTIVE MEDIUM THEORY that the people such as Norris (1985) propose calculates the elastic modulus K of the rock containing binary mineral constituent ^*and μ ^*, it is characterized in that, by a kind of mineral medium as a setting, adding another kind of mineral until obtain net result to it gradually:

$(1-y)\frac{d}{\mathrm{dy}}\left[K^{*}\left(y\right)\right]=(K_2-K^{*})P^{(*2)}\left(y\right)---\left(3\right)$

$(1-y)\frac{d}{\mathrm{dy}}\left[{\mathrm{\μ}}^{*}\left(y\right)\right]=({\mathrm{\μ}}_2-{\mathrm{\μ}}^{*})Q^{(*2)}\left(y\right)---\left(4\right)$

Wherein, y is the increment of each the second mineral constituent added, P ^{(* 2)}and Q ^{(* 2)}represent the form of the 2nd kind of mineral in background media respectively, its expression formula comprises the aspect ratio of mineral grain and hole.

(3), self-compatibility approximate (Self-Consistent Approximation) is theoretical

Berryman (1980) etc. improves self-compatibility approximation theory, can ask for the elastic modulus of the rock containing the mineral constituent of N phase with

${\mathrm{\Σ}}_{i=1}^N{x}_i(K_i-K_{\mathrm{SC}}^{*})P^{*i}=0---\left(5\right)$

${\mathrm{\Σ}}_{i=1}^N{x}_i({\mathrm{\μ}}_i-{\mathrm{\μ}}_{\mathrm{SC}}^{*})Q^{*i}=0---\left(6\right)$

Wherein, x _ibe the volumn concentration of i-th kind of mineral constituent, K _iand μ _ibe bulk modulus and the modulus of shearing of i-th kind of mineral constituent, P ^{* i}and Q ^{* i}be respectively the geometric factor of i-th kind of mineral constituent, comprise mineral grain and pore components parameter.

In above-mentioned three kinds of theoretical models, Xu-White (1996) will models applying is in sand-mud binary mineral constituent system, and inverting pore components is also predicted with this shear wave velocity carrying out sandstone.Difference EFFECTIVE MEDIUM THEORY and self-compatibility approximation theory are often applied to the impact of carbonate porosity aspect ratio on rock speed.The routine application of these models is general adopts the elastic modulus first calculating solid skeletal corresponding to dry hole gap, then applies the flow process that Gassmann fluid replaces the elastic modulus of theory calculate fluid saturated rock.

Current petrophysical model not yet takes into full account the singularity of the compact reservoir micromechanisms such as mud shale, comprise: mineral constituent is various, micropore structure is complicated, and low-porosity, low-permeability make Gassmann fluid replace the theoretical problem such as inapplicable, make the rock physics modeling of mud shale compact reservoir and pore components inverting have difficulties.

In addition, in shear wave velocity prediction, also need to set up accurate petrophysical model, under the common constraint of mineral constituent, microscopic void form, predict shear wave velocity.Conventional method, generally for log data, adopts linear or non-linear experimental formula to predict shear wave velocity by velocity of longitudinal wave, and the limitation of this method is that in experimental formula, choosing of coefficient has very strong regionality; Meanwhile, because these class methods have presupposed the relation of P-and S-wave velocity, therefore have ignored the change of Rock Poisson Ratio Using, and Poisson ratio is the important parameter determining compact reservoir fragility, reflection rock pressure break.

Summary of the invention

For overcoming the defect existing for prior art, the invention provides a kind of unconventional fine and close shale reservoir pore texture inverting and S-Wave Velocity Predicted Method, on the basis considering the diversity of unconventional mud shale compact reservoir mineral constituent, the complicacy of micropore structure, for compact reservoir microscopic void and fracture evaluation, shear wave velocity prediction provide new method.

To achieve these goals, following scheme is adopted:

The inverting of compact reservoir pore components and S-Wave Velocity Predicted Method, comprise the following steps: 1) obtain log data, comprise well depth, each mineral constituent percent by volume, TOC content, factor of porosity, oil-containing, gas, water saturation, well logging velocity of longitudinal wave; 2) each mineral constituent, kerogen and oil, gas, the bulk modulus of water, modulus of shearing, density is obtained; 3) for a well logging sampled point, choose between 0.001 to 1, be spaced apart the pore components a=a of 0.001 _n, wherein: a ₀=0.001< ... a _n<a _n+1<a _n=1, calculate each pore components a by petrophysical model _ncorresponding P-wave And S analog rate Vp _nwith Vs _n; 4) the described compressional wave analog rate Vp calculated by petrophysical model is calculated _nwith the difference of the velocity of longitudinal wave Vp obtained that logs well, ask for and store making | Vp _n-Vp| reaches minimizing pore components a _nwith shear wave analog rate Vs _n; 5) said process is repeated to each well logging sampled point, obtain the pore components a curve of inverting and the shear wave velocity Vs curve of prediction.

Present invention also offers the modeling method of unconventional fine and close shale reservoir petrophysical model, the method is the core of pore components inverting and shear wave velocity prediction, comprising: the bulk modulus, modulus of shearing, the density that 1) obtain Rock Matrix mineral constituent; 2) bulk modulus, modulus of shearing, the density of hole salt solution is obtained; 3) log data factor of porosity is obtained; 4) pore components is set; 5) by the bulk modulus of theory calculate kerogen, oil, gas mixture, modulus of shearing, density; 6) percent by volume of above-mentioned Rock Matrix mineral constituent, hole, kerogen potpourri is obtained by log data; 7) bulk modulus, modulus of shearing, the density of fine and close shale reservoir rock is calculated by rock physics self-compatibility approximation theory (SCA); 8) bulk modulus, modulus of shearing, density are converted to P-and S-wave velocity Vp and Vs.

Relative to prior art, Advantageous Effects of the present invention is as follows: in petrophysical model, consider the diversity of shale reservoir mineral constituent, the complicacy of micropore structure, what provide is that the pore components inversion method of core provides new parameter for compact reservoir microscopic void and fracture evaluation with petrophysical model, the S-Wave Velocity Predicted Method provided is using pore components as constrained parameters, and more traditional empirical fit mode has more theory advantage.

Accompanying drawing explanation

Fig. 1 predicts process flow diagram according to the pore components inverting of the embodiment of the present invention and shear wave velocity;

Fig. 2 is the rock physics modeling procedure figure according to the embodiment of the present invention;

Fig. 3 is Barnett Well 1 log data line chart;

Fig. 4 is the pore components inversion result line chart of Barnett Well 1;

Fig. 5 is Barnett Well 2 log data line chart;

Fig. 6 is the pore components inversion result line chart of Barnett Well 2;

Fig. 7 is that Barnett Well 1 shear wave velocity predicts the outcome line chart;

Fig. 8 is that Barnett Well 2 shear wave velocity predicts the outcome line chart.

Embodiment

Fig. 1 is the compact reservoir pore components inverting of the embodiment of the present invention and the process flow diagram of S-Wave Velocity Predicted Method, and the method comprises:

Step S101, obtains log data, comprises percent by volume, TOC content, factor of porosity, oil-containing, gas, water saturation, the well logging velocity of longitudinal wave of well depth, each mineral constituent mineral such as () clay, quartz, carbonatites;

Step S102, obtains each mineral constituent, kerogen and oil, gas, the bulk modulus of water, modulus of shearing and density;

Step S103, for each well logging sampled point, chooses between 0.001 to 1, is spaced apart the pore components a=a of 0.001 _n(wherein a ₀=0.001< ... a _n<a _n+1<a _n=1), each pore components a is calculated by petrophysical model _ncorresponding P-and S-wave velocity Vp (simulation) n and Vs (simulation) n;

Step S104, calculates by the velocity of longitudinal wave Vp (simulation) of rock physical modeling _nwith the difference of the velocity of longitudinal wave Vp (observation) observed that logs well, ask for | Vp (simulation) _n-Vp (observation) | minimal value, and store make | Vp (simulation) _n-Vp (observation) | reach minimizing pore components a _nwith shear wave velocity Vs (simulation) _n;

Step S105, repeats said process to each well logging sampled point, obtains the pore components a curve of inverting and the shear wave velocity Vs curve of prediction.

Can be seen by above description, by considering the fine and close diversity of shale reservoir mineral constituent, the complicacy of micropore structure in petrophysical model, in inversion algorithm using pore components as fitting parameter, can inverting pore components, for compact reservoir microscopic void and fracture evaluation provide new parameter; Can predict shear wave velocity using pore components as constrained parameters, this speed can be used as the prediction to shear wave velocity under lithology and micropore structure constraint, and more traditional empirical fit mode has more theory advantage.

In above-mentioned steps S103, the petrophysical model of fine and close shale reservoir is the key realizing pore components inverting and shear wave velocity prediction, and the detailed process of rock physics modeling as shown in Figure 2, comprising:

Step S201, obtains bulk modulus, modulus of shearing and the density of Rock Matrix mineral constituent (clay, quartz, carbonatite mineral etc.);

Step S202, obtains bulk modulus, modulus of shearing, the density of hole salt solution; Obtain log data factor of porosity; Setting pore components;

Step S203, by the bulk modulus of theory calculate kerogen, oil, gas mixture, modulus of shearing and density;

Step S204, is obtained the percent by volume of above-mentioned Rock Matrix mineral constituent, hole, kerogen potpourri by log data;

Step S205, is calculated bulk modulus, modulus of shearing, the density of fine and close shale reservoir rock by rock physics self-compatibility approximation theory (SCA);

Step S206, is converted to P-and S-wave velocity Vp and Vs by bulk modulus, modulus of shearing, density.

Below provide an example, this example utilizes the log data from Barnett shale reservoir.Figure 3 shows that the log data of first well Barnett Well 1, Barnett shale covers and is respectively Marble Falls and Ellenburger carbonatite with underlying formation.According to the said method inverting compact reservoir pore components that the present invention proposes, acquired results as shown in Figure 4.Fig. 4 a is depicted as the negative logarithm-Log of pore components a ₁₀why a (), represent with its negative logarithm, is because pore components variation range is very large, crosses over 10 ⁰to 10 ^-3three orders of magnitude.Close to 0, the numerical value that pore components bears logarithm represents that pore shape is more tending towards spherical, numerical value larger expression hole is longer and narrower.In addition, as shown in Figure 3, the logging trace due to P-wave And S is all known, can respectively by P-wave And S inverting pore components, inversion result is represented by black in Fig. 4 a, Grey curves respectively, can see that the two is basically identical, also reflect the stability of this inversion method from another point of view.Fig. 4 b is factor of porosity logging trace; Fig. 4 c is by aspect ratio a and factor of porosity the fracture density of definition equally, Figure 5 shows that the log data of Barnett shale reservoir second mouthful of well Barnett Well 2, Fig. 6 is corresponding pore components inversion result.

Fig. 4 a and Fig. 6 a is by the pore components of P-wave And S inverting, can see that the pore components change of Barnett shale is not obvious, and the pore components change on Marble Falls and Ellenburger country rock stratum is violent, this shows that Barnett shale mesoporosity structure is more stable, and mesoporosity, the country rock stratum structural instability of its carbonatite.Inversion result conforms to geological observation data, also theoretical with petrology consistent: although namely shale mineral constituent is complicated, clay mineral wherein hinders the growth in hole and crack; Although carbonatite mineral constituent is simple, is subject to the impact of the physics chemical action such as terrestrial stress, corrosion and produces hole and crack.

Fig. 7 a and Fig. 8 a is respectively the shear wave velocity being predicted the two mouthfuls of wells obtained by this patent method, the prediction of shear wave velocity by the pore components in Fig. 7 b and Fig. 8 b as constraint.The actual P-and S-wave velocity recorded is represented by black curve, predicts that the shear wave velocity obtained is represented by Grey curves.Can see, the predicted value of shear wave velocity and measured value have good degree of agreement, demonstrate the effect of the method.

Claims (1)

1. compact reservoir pore components inverting and S-Wave Velocity Predicted Method, comprise the following steps: 1) obtain log data, comprise well depth, each mineral constituent percent by volume, TOC content, factor of porosity, oil-containing, gas, water saturation, well logging velocity of longitudinal wave; 2) each mineral constituent, kerogen and oil, gas, the bulk modulus of water, modulus of shearing, density is obtained; 3) for a well logging sampled point, choose between 0.001 to 1, be spaced apart the pore components a=a of 0.001 _n, wherein: a ₀=0.001< ... a _n<a _n+1<a _n=1, calculate each pore components a by petrophysical model _ncorresponding P-wave And S analog rate Vp _nwith Vs _n; 4) the described compressional wave analog rate Vp calculated by petrophysical model is calculated _nwith the difference of the velocity of longitudinal wave Vp obtained that logs well, ask for and store making | Vp _n-Vp| reaches minimizing pore components a _nwith shear wave analog rate Vs _n; 5) said process is repeated to each well logging sampled point, obtain the pore components a curve of inverting and the shear wave velocity Vs curve of prediction;

Wherein: calculate P-wave And S analog rate by petrophysical model and comprise the following steps: the bulk modulus, modulus of shearing, the density that 1) obtain Rock Matrix mineral constituent; 2) bulk modulus, modulus of shearing, the density of hole salt solution is obtained; 3) log data factor of porosity is obtained; 4) pore components is set; 5) by the bulk modulus of theory calculate kerogen, oil, gas mixture, modulus of shearing, density; 6) percent by volume of above-mentioned Rock Matrix mineral constituent, hole, kerogen potpourri is obtained by log data; 7) bulk modulus, modulus of shearing, the density of fine and close shale reservoir rock is calculated by rock physics self-compatibility approximation theory SCA; 8) bulk modulus, modulus of shearing, density are converted to P-wave And S analog rate Vp and Vs.